简介:Inthispaper,thephotonicbandgapofphotoniccrystalswithchiralandnegative-indexmaterialsalternatelyisinvestigated.Itisshownthatthiskindofphotoniccrystalexhibitsverywidephotonicbandgap.Thephotoniccrystalswithadefectlayerhaveanarrowdefectmodeinthebandgap,whichcanbeusedasaverygoodfilteringmaterialbychoosingtheparametersofthedefectlayerproperly.
简介:Weintroduceanewmodelofone-dimensional(1D)photoniccrystalcomposedofalternatelyarrangedRHMandLHMlayerswithpositiveandnegativerefractiveindicesrespectively,forwhichthetransmissionspectraofthemodelarecalculatednumericallywiththetransfermatrixmethod,andtheband-gapstructureandthepolarizationpropertiesareanalyzed.Wefoundthattheintroductionofnegativerefractiveindexlayers(i.e.LHMmediumlayers)givesrisetosomepeculiarband-gapstructureandpolarizationpropertiesasfollows.Firstly,theforbiddenbandsareextremelywideandthetransmissionbandsareverysharpwithoutoscillation;andsecondly,thechangeofincidentanglehasdifferentinfluencesontheforbiddenbandsofTEandTMmodes.FortheTMmode,theforbiddenbandwidthdecreasessubstantiallyandfinallyvanishes,andfortheTEmodewithcentralwavelength,thetotalreflectionhappensatanyincidentangle.
简介:Atunablenegativecoefficientband-passmicrowavephotonicfilter(MPF)withimprovedmainlobe-to-sidelobesup-pressionratio(MSSR)byaSagnacinterferometer(SI)isexperimentallydemonstrated.ThenegativecoefficientcharacteristicofMPFisachievedbyusingthephasemodulationtechnology.Thecentralfrequencyoftheband-passMPFistunablecontinuouslybychangingthewavelengthseparationofmulti-wavelengthopticalcarriers.A38-tapnegativecoefficientband-passMPFwhoseMSSRisincreasedbyabout6.371dBisachievedinexperimentbyapodizingthetapcoefficientwiththeSagnacinterferometer.
简介:Thebandgappropertiesofone-dimensionalphotoniccrystalswithadefectlayerofnegativerefractiveindexmaterialsarestudied.Thedefectmodewidthisbiggerthanthatofconventionalone-dimensionalphotoniccrystalswithadefectlayerofpositiverefractiveindexmaterials.Thedefectmodeoftheformerisdifferentfromthatofthelatter,shiftstowardsthedirectionofhighfrequency(shortwavelength),andhasabiggershiftingvelocity.Furthermoretheeffectsonthetransmissionpropertiesoftheformerphotoniccrystalscausedbychangeinthepositionofthedefectlayerofnegativerefractiveindexareinvestigated.Finallytheopticalenhancementoftheformerphotoniccrystalsisalsoinvestigated.